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1/*
2 * linux/fs/ext4/hash.c
3 *
4 * Copyright (C) 2002 by Theodore Ts'o
5 *
6 * This file is released under the GPL v2.
7 *
8 * This file may be redistributed under the terms of the GNU Public
9 * License.
10 */
11
12#include <linux/fs.h>
13#include <linux/jbd2.h>
14#include <linux/cryptohash.h>
15#include "ext4.h"
16
17#define DELTA 0x9E3779B9
18
19static void TEA_transform(__u32 buf[4], __u32 const in[])
20{
21 __u32 sum = 0;
22 __u32 b0 = buf[0], b1 = buf[1];
23 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
24 int n = 16;
25
26 do {
27 sum += DELTA;
28 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
29 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
30 } while (--n);
31
32 buf[0] += b0;
33 buf[1] += b1;
34}
35
36
37/* The old legacy hash */
38static __u32 dx_hack_hash_unsigned(const char *name, int len)
39{
40 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
41 const unsigned char *ucp = (const unsigned char *) name;
42
43 while (len--) {
44 hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
45
46 if (hash & 0x80000000)
47 hash -= 0x7fffffff;
48 hash1 = hash0;
49 hash0 = hash;
50 }
51 return hash0 << 1;
52}
53
54static __u32 dx_hack_hash_signed(const char *name, int len)
55{
56 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
57 const signed char *scp = (const signed char *) name;
58
59 while (len--) {
60 hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
61
62 if (hash & 0x80000000)
63 hash -= 0x7fffffff;
64 hash1 = hash0;
65 hash0 = hash;
66 }
67 return hash0 << 1;
68}
69
70static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
71{
72 __u32 pad, val;
73 int i;
74 const signed char *scp = (const signed char *) msg;
75
76 pad = (__u32)len | ((__u32)len << 8);
77 pad |= pad << 16;
78
79 val = pad;
80 if (len > num*4)
81 len = num * 4;
82 for (i = 0; i < len; i++) {
83 if ((i % 4) == 0)
84 val = pad;
85 val = ((int) scp[i]) + (val << 8);
86 if ((i % 4) == 3) {
87 *buf++ = val;
88 val = pad;
89 num--;
90 }
91 }
92 if (--num >= 0)
93 *buf++ = val;
94 while (--num >= 0)
95 *buf++ = pad;
96}
97
98static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
99{
100 __u32 pad, val;
101 int i;
102 const unsigned char *ucp = (const unsigned char *) msg;
103
104 pad = (__u32)len | ((__u32)len << 8);
105 pad |= pad << 16;
106
107 val = pad;
108 if (len > num*4)
109 len = num * 4;
110 for (i = 0; i < len; i++) {
111 if ((i % 4) == 0)
112 val = pad;
113 val = ((int) ucp[i]) + (val << 8);
114 if ((i % 4) == 3) {
115 *buf++ = val;
116 val = pad;
117 num--;
118 }
119 }
120 if (--num >= 0)
121 *buf++ = val;
122 while (--num >= 0)
123 *buf++ = pad;
124}
125
126/*
127 * Returns the hash of a filename. If len is 0 and name is NULL, then
128 * this function can be used to test whether or not a hash version is
129 * supported.
130 *
131 * The seed is an 4 longword (32 bits) "secret" which can be used to
132 * uniquify a hash. If the seed is all zero's, then some default seed
133 * may be used.
134 *
135 * A particular hash version specifies whether or not the seed is
136 * represented, and whether or not the returned hash is 32 bits or 64
137 * bits. 32 bit hashes will return 0 for the minor hash.
138 */
139int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
140{
141 __u32 hash;
142 __u32 minor_hash = 0;
143 const char *p;
144 int i;
145 __u32 in[8], buf[4];
146 void (*str2hashbuf)(const char *, int, __u32 *, int) =
147 str2hashbuf_signed;
148
149 /* Initialize the default seed for the hash checksum functions */
150 buf[0] = 0x67452301;
151 buf[1] = 0xefcdab89;
152 buf[2] = 0x98badcfe;
153 buf[3] = 0x10325476;
154
155 /* Check to see if the seed is all zero's */
156 if (hinfo->seed) {
157 for (i = 0; i < 4; i++) {
158 if (hinfo->seed[i])
159 break;
160 }
161 if (i < 4)
162 memcpy(buf, hinfo->seed, sizeof(buf));
163 }
164
165 switch (hinfo->hash_version) {
166 case DX_HASH_LEGACY_UNSIGNED:
167 hash = dx_hack_hash_unsigned(name, len);
168 break;
169 case DX_HASH_LEGACY:
170 hash = dx_hack_hash_signed(name, len);
171 break;
172 case DX_HASH_HALF_MD4_UNSIGNED:
173 str2hashbuf = str2hashbuf_unsigned;
174 case DX_HASH_HALF_MD4:
175 p = name;
176 while (len > 0) {
177 (*str2hashbuf)(p, len, in, 8);
178 half_md4_transform(buf, in);
179 len -= 32;
180 p += 32;
181 }
182 minor_hash = buf[2];
183 hash = buf[1];
184 break;
185 case DX_HASH_TEA_UNSIGNED:
186 str2hashbuf = str2hashbuf_unsigned;
187 case DX_HASH_TEA:
188 p = name;
189 while (len > 0) {
190 (*str2hashbuf)(p, len, in, 4);
191 TEA_transform(buf, in);
192 len -= 16;
193 p += 16;
194 }
195 hash = buf[0];
196 minor_hash = buf[1];
197 break;
198 default:
199 hinfo->hash = 0;
200 return -1;
201 }
202 hash = hash & ~1;
203 if (hash == (EXT4_HTREE_EOF_32BIT << 1))
204 hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
205 hinfo->hash = hash;
206 hinfo->minor_hash = minor_hash;
207 return 0;
208}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext4/hash.c
4 *
5 * Copyright (C) 2002 by Theodore Ts'o
6 */
7
8#include <linux/fs.h>
9#include <linux/compiler.h>
10#include <linux/bitops.h>
11#include "ext4.h"
12
13#define DELTA 0x9E3779B9
14
15static void TEA_transform(__u32 buf[4], __u32 const in[])
16{
17 __u32 sum = 0;
18 __u32 b0 = buf[0], b1 = buf[1];
19 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
20 int n = 16;
21
22 do {
23 sum += DELTA;
24 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
25 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
26 } while (--n);
27
28 buf[0] += b0;
29 buf[1] += b1;
30}
31
32/* F, G and H are basic MD4 functions: selection, majority, parity */
33#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
34#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
35#define H(x, y, z) ((x) ^ (y) ^ (z))
36
37/*
38 * The generic round function. The application is so specific that
39 * we don't bother protecting all the arguments with parens, as is generally
40 * good macro practice, in favor of extra legibility.
41 * Rotation is separate from addition to prevent recomputation
42 */
43#define ROUND(f, a, b, c, d, x, s) \
44 (a += f(b, c, d) + x, a = rol32(a, s))
45#define K1 0
46#define K2 013240474631UL
47#define K3 015666365641UL
48
49/*
50 * Basic cut-down MD4 transform. Returns only 32 bits of result.
51 */
52static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
53{
54 __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
55
56 /* Round 1 */
57 ROUND(F, a, b, c, d, in[0] + K1, 3);
58 ROUND(F, d, a, b, c, in[1] + K1, 7);
59 ROUND(F, c, d, a, b, in[2] + K1, 11);
60 ROUND(F, b, c, d, a, in[3] + K1, 19);
61 ROUND(F, a, b, c, d, in[4] + K1, 3);
62 ROUND(F, d, a, b, c, in[5] + K1, 7);
63 ROUND(F, c, d, a, b, in[6] + K1, 11);
64 ROUND(F, b, c, d, a, in[7] + K1, 19);
65
66 /* Round 2 */
67 ROUND(G, a, b, c, d, in[1] + K2, 3);
68 ROUND(G, d, a, b, c, in[3] + K2, 5);
69 ROUND(G, c, d, a, b, in[5] + K2, 9);
70 ROUND(G, b, c, d, a, in[7] + K2, 13);
71 ROUND(G, a, b, c, d, in[0] + K2, 3);
72 ROUND(G, d, a, b, c, in[2] + K2, 5);
73 ROUND(G, c, d, a, b, in[4] + K2, 9);
74 ROUND(G, b, c, d, a, in[6] + K2, 13);
75
76 /* Round 3 */
77 ROUND(H, a, b, c, d, in[3] + K3, 3);
78 ROUND(H, d, a, b, c, in[7] + K3, 9);
79 ROUND(H, c, d, a, b, in[2] + K3, 11);
80 ROUND(H, b, c, d, a, in[6] + K3, 15);
81 ROUND(H, a, b, c, d, in[1] + K3, 3);
82 ROUND(H, d, a, b, c, in[5] + K3, 9);
83 ROUND(H, c, d, a, b, in[0] + K3, 11);
84 ROUND(H, b, c, d, a, in[4] + K3, 15);
85
86 buf[0] += a;
87 buf[1] += b;
88 buf[2] += c;
89 buf[3] += d;
90
91 return buf[1]; /* "most hashed" word */
92}
93#undef ROUND
94#undef K1
95#undef K2
96#undef K3
97#undef F
98#undef G
99#undef H
100
101/* The old legacy hash */
102static __u32 dx_hack_hash_unsigned(const char *name, int len)
103{
104 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
105 const unsigned char *ucp = (const unsigned char *) name;
106
107 while (len--) {
108 hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
109
110 if (hash & 0x80000000)
111 hash -= 0x7fffffff;
112 hash1 = hash0;
113 hash0 = hash;
114 }
115 return hash0 << 1;
116}
117
118static __u32 dx_hack_hash_signed(const char *name, int len)
119{
120 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
121 const signed char *scp = (const signed char *) name;
122
123 while (len--) {
124 hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
125
126 if (hash & 0x80000000)
127 hash -= 0x7fffffff;
128 hash1 = hash0;
129 hash0 = hash;
130 }
131 return hash0 << 1;
132}
133
134static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
135{
136 __u32 pad, val;
137 int i;
138 const signed char *scp = (const signed char *) msg;
139
140 pad = (__u32)len | ((__u32)len << 8);
141 pad |= pad << 16;
142
143 val = pad;
144 if (len > num*4)
145 len = num * 4;
146 for (i = 0; i < len; i++) {
147 val = ((int) scp[i]) + (val << 8);
148 if ((i % 4) == 3) {
149 *buf++ = val;
150 val = pad;
151 num--;
152 }
153 }
154 if (--num >= 0)
155 *buf++ = val;
156 while (--num >= 0)
157 *buf++ = pad;
158}
159
160static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
161{
162 __u32 pad, val;
163 int i;
164 const unsigned char *ucp = (const unsigned char *) msg;
165
166 pad = (__u32)len | ((__u32)len << 8);
167 pad |= pad << 16;
168
169 val = pad;
170 if (len > num*4)
171 len = num * 4;
172 for (i = 0; i < len; i++) {
173 val = ((int) ucp[i]) + (val << 8);
174 if ((i % 4) == 3) {
175 *buf++ = val;
176 val = pad;
177 num--;
178 }
179 }
180 if (--num >= 0)
181 *buf++ = val;
182 while (--num >= 0)
183 *buf++ = pad;
184}
185
186/*
187 * Returns the hash of a filename. If len is 0 and name is NULL, then
188 * this function can be used to test whether or not a hash version is
189 * supported.
190 *
191 * The seed is an 4 longword (32 bits) "secret" which can be used to
192 * uniquify a hash. If the seed is all zero's, then some default seed
193 * may be used.
194 *
195 * A particular hash version specifies whether or not the seed is
196 * represented, and whether or not the returned hash is 32 bits or 64
197 * bits. 32 bit hashes will return 0 for the minor hash.
198 */
199int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
200{
201 __u32 hash;
202 __u32 minor_hash = 0;
203 const char *p;
204 int i;
205 __u32 in[8], buf[4];
206 void (*str2hashbuf)(const char *, int, __u32 *, int) =
207 str2hashbuf_signed;
208
209 /* Initialize the default seed for the hash checksum functions */
210 buf[0] = 0x67452301;
211 buf[1] = 0xefcdab89;
212 buf[2] = 0x98badcfe;
213 buf[3] = 0x10325476;
214
215 /* Check to see if the seed is all zero's */
216 if (hinfo->seed) {
217 for (i = 0; i < 4; i++) {
218 if (hinfo->seed[i]) {
219 memcpy(buf, hinfo->seed, sizeof(buf));
220 break;
221 }
222 }
223 }
224
225 switch (hinfo->hash_version) {
226 case DX_HASH_LEGACY_UNSIGNED:
227 hash = dx_hack_hash_unsigned(name, len);
228 break;
229 case DX_HASH_LEGACY:
230 hash = dx_hack_hash_signed(name, len);
231 break;
232 case DX_HASH_HALF_MD4_UNSIGNED:
233 str2hashbuf = str2hashbuf_unsigned;
234 case DX_HASH_HALF_MD4:
235 p = name;
236 while (len > 0) {
237 (*str2hashbuf)(p, len, in, 8);
238 half_md4_transform(buf, in);
239 len -= 32;
240 p += 32;
241 }
242 minor_hash = buf[2];
243 hash = buf[1];
244 break;
245 case DX_HASH_TEA_UNSIGNED:
246 str2hashbuf = str2hashbuf_unsigned;
247 case DX_HASH_TEA:
248 p = name;
249 while (len > 0) {
250 (*str2hashbuf)(p, len, in, 4);
251 TEA_transform(buf, in);
252 len -= 16;
253 p += 16;
254 }
255 hash = buf[0];
256 minor_hash = buf[1];
257 break;
258 default:
259 hinfo->hash = 0;
260 return -1;
261 }
262 hash = hash & ~1;
263 if (hash == (EXT4_HTREE_EOF_32BIT << 1))
264 hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
265 hinfo->hash = hash;
266 hinfo->minor_hash = minor_hash;
267 return 0;
268}